Ignition device for air compressors



oen 22, 1929. R P, PESQ'RA 1,732,694

IGNITION DEVICE FOR AIR COMIRESSORS l v j mylzless 72a 15V/fab! rfmm LW ,ier ZYX/Mb O ct. l22, 1929. R. P'. PESCARA IGNITION DEVICE FOR AIR COMPRESSGRS Filed April 6, 1927 '2 shuts-sheet 2 Patenied oa. z2. 1929 UNITED STATES 'PATENT 4ori-ice- RAL' :eurams PESCARA, or rams, FRANCE remmen D1-1v1carort AIR coMPREssoRs.

Application tiled April' 6, 1927, Serial No. 181,555, and in France April 9, 1926.

' My invention relates'to air compressors of vthe type in which two'. pistons are driven directly by internal combustion, said pistons being synchronized mechanically and pari l ticularly to the ignition of the explosive mixture-driving said pistons.

The device forming the subject of the present application is particularly'adapted to be used with the typeof compressor disclosed in my co-'pending applications, Serial No. 177 ,938 filed March 24, 1927; and Serial No. 17 7,939 filed March 24, 1927, respectively.

One of the objects ofthe invention is to provide an ignition device for an apparatus 1 of the character indicated which shallY assure igniting of the explosive mixture in the cylinder after its preliminary compression and at the time the pistons are near the end of their stroke during normal operation of the apparatus. I

Another object of the invention is to provide a means for automatically rendering the air compressor inoperative when the compressed air in the storage tank of the apparatus rises to its normal value and for automatically rendering said air compressor operative again when the pressure falls belowlits normal value. Y

Still another'object of the invention is to maintain the operation of the pistons While operating at no load by igniting the explo" sive mixture in the motor cylinder between the pistons only when the pressure of.,said explosive mixture due to itscompression shall i have. attained a certain predetermined value and in such a manner that the energy developed by the subsequent combustion will be suiiicient to assure the replacement of. the

burned gases by a newv charge ofexplosive 0 mixture.

Other objects of the invention will beobvious to those skilled in the art inthe following specification when taken with thel accompanying drawing in Which"-` Fig. 1 represents a diagrammatic detail view of my device partly in. section on a large scale' Fig. 2 is a broken section through the distributer taken on the line 2-2 of Fig. 1;

Fig. 3 is a development of the surface of the periphery of the distributer showing the arrangement of the brushes with respect to the distributer contacts; and

Fig. 4 is a diagram showing my improved ignition device-as applied to-'a compressor;` 55

It willv be remembered that in the co-pending applications, above mentioned, the compressors were provided with a synchronizing mechanism with an oscillating member which turned throughV less than a complete revolu- 6I tion during each oscillation. This oscillating member provides the driving means for the device forming the subject of the present application. a

l Referring to the drawing, Fig. 4 shows ci diagrammatically a compressor similar to the type above mentioned represented generally at A provided with direct driven,- substantially free-flying compressing pistons C each fitted in a compressing cylinder D provided 7i with an air outlet a.- Said pistons C are interconnected with a synchronizing device B of the oscillatable type requiring a relatively small amount of power for its operation.

Only the essential elements of the compressor A necessary for an understanding of theoperation yof my improved ignition device have been illustrated since the details thereof are fully disclosed in my copending applica. tions, above mentioned and have no particular 80 bearing on lmy present invention. 'f

A rotatable shaft 12 is adapted to be driven by the synchronizingl device B, above mentioned. Attached to said shaft is a circular distributer 13 of insulating material. Said distributer carries a pawl 14 pivoted at 15 which makes'contact with a. platinum screw 16 also carried by the distributer. post 17 carries a regulating screw 18 and a ma 19 foriimiting the distance said paw-1 my op move away from its contact screw 16.. A small bar 20 is adapted to slide in a guide 21 lfixed to the distributer'l.' As shown in Fig. 2, the bar 20 is provided with a slot near the center of said distributer through which the pawl 14 extends. The outer extremity of bar V'2ll'zis furnished with 'a small piece of insulating material as shown at 22.

A spring 23 is attached at one end of the bar L20 and itsother end is fastened to a bell 100 crank 26, pivoted to distributer 13 at 27. The spring 23 normally holds members 16 and 14 Separated.I The periphery of distributer 13 carries two metal contacts 24 and 25. The/contact 24 is placed in electrical communication with the screw 16 vwhile the contact 25 is electrically connected to the pivot 27 through pawl 14, spring -23 and lever 26. As show n in Fig. 3, the extremities of said contacts are arranged in overlapping relation. Arranged concentrically with the distributer 13 is a casing 28 of insulating material and which carries two carbon brushes 29 and 30 in electrical communication with the binding posts 31, 32 fixed to said casing. As shown in Fig. 3 the brushes 29 and 30 are disposed on opposite edgesof the periphery of the distributer in lsuch a manner that the 20. brush 29 contacts with'the contact24 on the longer portion thereof while the brush 30 can only contact with member 24y on its shorter portion. The casing 28 is closed by a cover 229 screwed thereon and at its center carries an abutment for the extremity 9 of the bellcrank lever 26. Said casino is provided with a cam member 33 which arsagainst the .extremity 22 of the bar 20. The mechanism above described is fur! nished with a pressure operated switch which comprises a coiled tube 34, connected to the storage tank T of the air compressor A` by means of a pipe 35. The other extremity car- 4 ries a projection 36 which engages a slot 37 on I the en d of a lever 38, pivoted on a stud 39. A brush is attached to the other end of said 'lever and extends perpendicularl'y therefrom. The brush 40 is insulated from the lever 38 in any convenient manner or the lever 38 may be constructed of insulating material.

The brush 40 is adapted to slide over a plurality of contacts 41,42, 43 insulated from each other and from the apparatus.

The switch -is further provided with two stops 44 and 45 which limit the movement of lever 38. Said lever is provided with a sector portion disposed concentrically with respect to its pivot 39 and provided with notches 46 and 47. A ball 48 is adapted to bear against said sector portion by means of a spring 49 and a regulating screw 5() mounted in a suitable support 51.

The low tension circuit of my device includes a low voltage winding 52 of the usual spark-coil, one terminal of which is connected to the earth. The other terminal ofsaid coil winding is connected toy one of the terminals 53 of a suitable generator such as a battery 54. The other terminal of said battery 54 is 6o connected .by means of a wire 55 to the contact 41. Two conductors 56 and 57 connect the contacts 42 and 43 to binding posts 31 and 32 respectively. The shaft 12 and all the metal elements in contact therewith, namely j the pawl 14 and the contact 25 are grounded.

represents that occupied by the bar 20 when The high tension circuit comprises simply a high tension coi1`58 in inductive relation with coil 52. One terminal of coil 58 is grounded while the remaining terminal is N ormal operation When the air compressor 1s operating normally, the distributer 13 turns alternately in such a manner'that the bar 20 describes an angle equal to 360o-a (Fig. 1.). The position of the' bar in Fig. 1 is the position occupied when the pistons of the compressor have reached the end of their stroke in their movement toward each other. The position corresponding to the other side of the angle a the pistonshave attained-the end of their stroke in the direction from each other.

v 'When the distributer 13 start sto rotate, bar 20 moves under the action of centrifugal force and closes the contacts 14 and 16 by carrying the former contact with it.

When the pistons reach the end of their stroke, the distributer slows down and the spring'23 draws the bar 20 toward the center of the distributer carrying with it thepawl 14 and breaking the low tension circuit which \eXtends'i`rom the ground, paw'l 14, vcontact 16, contact 24, brush 29, binding-post 31, wire 56, contact 42, brush 40, contact 41, wire ,55, battery 54, wire 53, low-tension winding 52 100 and thence to the ground. The rupture oi the low tension circuit produces the necessary sparks for firing the motor cylinder.

lVhen the pistons of the compressor are driven forward by the impact of the explosion thus produced, the distributer 13 is turned in the direction of the arrow 61. Rotation of the said distributer reestablishes the contact between members 14 and `16 thus closing the low tension circuit, above traced. Continued rotation brings 'the brush 29, which is in contact with contact 24, into electricalcommunication with contact 25. This changing from one contact to another has no ei'ect `on the circuit because the brush 29 is made large 115 enough to bridge the contacts 24, 25'in assing as shown in dottedjlines at 129 in Fig. 3. Before the change took place contact 24 was grounded through pawl 14 and bar 20 drawing said pawl into contact with the screw 16, which as above described, is in electricalcommunication with the contact 24. Since contact 25 is in electrical communication with the lever -26 onthe frame of the machine which is grounded, the movement of the brush 29 from 125 one contact to the other has no effect on the circuit whatsoever.

When the energy imparted to the pistons is spent they arrive at the end of their stroke and the bar 20 of the distributer 13 occupies 130 'the position represented by `the upper side of the angle a. The spring 23 again over comes the centrifugal force imparted to bar 2O and opens the contacts 14, 16 as before. This time, however, no spark is produced in the spark-plug 60 due to the fact that the low tension circuit has been roundedl throu h brush 29 and contact 25 in ependently of t e contacts 14, 16.

Even with the apparatus functioning normally and the distributer alternating regularly, the angle 360oa is bound to vary slightly due to small irregularities in operation. As described more fully in my co-pending application Serial No. 181,554 tiled April 6, 1927, it is important that when the pistons `are furthest apart the distributor should-not be about to turn in the reverse direction of the arrow 61 because such a relation of the parts would produce a spark when the distributer moves in said reverse direction. That is why, among other reasons, that contact 24 is made relatively long in the direction opposite to arrow 61 with respect to brush 29. It will be obvious to those skilled in the art from the foregoing that should the distributer .be overJthrown in the direction opposite to the arrow 61 it'becomes necessary to stabilize the apparatus and the spark must be given even though the spring 23 is unable to overcome the centrifugal force of bar 20. The iring of the cylinder is assured by the cam 33 at a certain predetermined position of the distributer which raises the bar20 upon overthrow of the distributer and breaks the lowtension circuit. This is the reason why the contact 24 is extended beyond brush 29 in the direction of the arrow 61.

In orderto regulate the output of the compressor or simply to run the compressor abnormally, it is necessary to provide a means for advancing and retarding the spark. For

' this purpose the cover 229 screwed to the casing 28 bears against the extremity 9 of lever 26 and regulates the tension of spring 23 ac-l cording to the position it occupies. The greater the tension of spring 23 the sooner it can overcome the centrifugal force of bar 20 and hence the sooner the low tension circuit will be interrupted and vice-versa. In short, screwing thel cover 29 on the casing 28 ad- .l vances the spark and unscrewing said-cover retards it.

Operation) dum'ng idling As shown in Fig. 4 the tube 34 is attached to the storage tank T of the compressor a4 by means of pipe 35. When the pressure in said tank T is belownormal, the tube 34 is relaxed and the switch lever remains in thel position shown in Fig. 1, which position was assumed for the explanation of the normal operation of the apparatus. As the pressure in the storage tank T comes u to normal the tube becomes affected there y and tends to unwind.

This movement tends to move the lever l38', in contact with the stop 44, against the stop 45. But this force tending to move said lever is opposed by the ball 48 held in notch 47 by the spring 49. When the force tending to move lever 38 becomes sucient to overcome the pressure exerted against the ball by spring 49, the lever is abruptly thrown from the stop 44 to the stop 45. The pressure exerted by the spring 49 may be varied by turning the regulating screw 50' and hence the lever 38 may be made to move when the pressure in the storage tank T has attained any value desired.

The brush 40 'is' made large enough so that the low-tension circuit is not broken when-it passes froml contact 42 to 43 during movement of said brush across the space between said contacts. I

When the switch has moved to contact 43 the low-tension circuit is established from the ground to pawl 14, contact 16, Contact 24,

brush 30, binding-post 32, wire 57, contact 43,

the distributer slows down toward the end of its throw and the contacts 14, 16 are opened as before explained. But since the low tension circuit is established through the grounded contact 25 independently of contacts 14 and 16, the opening of said contacts has no effect thereon and no spark is produced in the motor cylinder.

From the foregoing it will be obvious that as'the pistons move away from each other t-he distributer 13 is turned in the direction of the arrow 61, but since the pistons have received no `energy -they are unable to coml press the air in their respective cylinders. The stroke of the pistons, therefore becomes less than normaland are. unable to uncover the admission and exhaust openings.

As a result the movement of distributer 13 is considerably reduced and the angle a consequently grows larger. No spark, however is produced during opening of contacts 14, 16 due to the particular arrangement of the brushes 29, 3() with respect to the overlapping contacts 24, 25, the brush 30 being always on y the grounded contact 25 when said openingn takes place. l

The parts are so arranged that when the pistons start to idle there is always an explosive mixture between themwhich is just sufficient to drive the pistonsto the normal end of their stroke. The pistons continue to reciprocate slower and slower compressing the explosive Inlxture between them over and over again.

It will be noted that during this reciproca-A 5 tion of the pistons the brush 30 passes com- K pletely over the overlapping portion of contact 24 in its path and that when the distributer reverses its direction of motion said brush is always in contact with 25. As the reciprocations of the pistons become sufiiciently rgduced the movement of the distributer also becomes reduced in proportion. There finally arrives a condition where the brush 30 no longer moves over on contact 25 when the distributor reverses its motion in 'the direction of the arrow 6l, but remains on contact 24 until the motion is reversed. This places the contacts 14, 16 again in the low tension l circuit and when said contacts are opened 2o by the spring 23 a spark is produced in the plug 60 in a manner already described. The pistons are driven in opposite directions by the force oit' the explosion with suiicient energy to assure scavenging of the cylinders and 25 the evacuation of the burned `gases as well as the introduction of a fresh charge of explosive mixture in the cylinder. At the same time the movement of the distributer becomes increased to that which it was when the compresser started to idle. The pistons' again start to reciprocate slower and slower and the same cycle of operations, above described,

is repeated. The device continues to operate lightly with only suiicient energy to keep it in mot-ion as long as the pressure remains normal in the storage tank.

Resumptzon of load When the pressure of the air in the storage tank T drops below normal, the coiled tube 34r again relaxes and moves the lever 38 from the stop to the stop 44, the ball 48 causing an abrupt action when moving from notch 46 to notch 47 as before.

The brush 4() is thus moved from the contact 43 back lto the contact 42 and reestablishes thelow-tension circuit. through the brush 29 as already described. As soon as the distribut-er 13 moves in the 50 direction opposite to that of arrow 61, the

charge of explosive mixture immediately becomes ignited upon the distributer slowing down as previously described. The compressor A then takes on load and continues to operate until t-he pressure in the storage tank vT is built up to normal.

` In order to make sure that the brush 29 will Abe on the contactv24 when the distributer 13 has completed its movement opposite to that of the arrow 61, the angular sector included by the contact 24 is made greaterthan the angle included between the two brushes 29 and 30. With this arrangement'no matter i' Y l how small the oscillations of the distributer may become they cannot descend beyond a certain limit determined lby the position o brush 30 with respect to contact 24. The

brush 29 will always, therefore, been contact 24 as soon as the distributer starts to move in the direction opposite to the arrow 61.

The pistons Cpick up the load very rapidly and reciprocate the full length of their stroke as soon as the switch lever 38 operates.l

The instrumentalities employed for admitting anexplosive mixture into the compressor A and for producing the exhaust thereof after iring'has not been disclosed since such means are well .known by those skilled in the art' and are not essential to an understanding of my invention as comprehended within the scope of the appended claims. The same observation is true of the inlet and outlet valves of the compressing cylinders.

Many variations in my apparatus may be made by those skilled in the art without dearting from my invention, since lYhat I claim is- 1. An ignition device for motor compressors having free-flying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism comprising a closed ignitioncircuit, means for normally opening said ignition circuit at regular intervals driven by an element of said stabilizing mechanism and means for automatically changing the intervals at which said circuit is opened.

2. An ignition device for motor compressors having free-,flying direct acting pistons interconnected by a mon-kinematic oscillating stabilizing mechanism comprising a closed ignition circuit, means driven by' an element of said stabilizing mechanism for normally opening said ignition circuit at regular intervals and means responsive to the pressure of the fluid compressed 4for automatically changing the intervals at which said circuit is opened.-

3. An ignition device for motor compressors having free-flying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism comprising means driven by an element of said stabilizing mechanism for supplying a Vspark to the motor cylinder at regular intervals `during operation under load and means for automatically suppressing certain of the sparks when said compressor starts to idle. 5w y 4. An ignition device for motor compressors having free-flying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism comprising a centrifugally operated di'stributer. driven by an element of said stabilizing mechanism for supplyinga spark to the motor cylinder at regular intervals during operation under load and pressure operated meansfor auto-V matically suppressing certain of the sparks when said compressor starts toidle.`

5. An igmtion device for motor'comprestrifugally operated distributer adapted to be oscillated through an angle less than 36()o by an element of said stabilizing mechanism, an ignition circuit connected to said distributer and means on said distributer for opening said ignition circuit when said distributer changes its direction of rotation and for rendering one of said opening operations ineffective.

6. An ignition device for motor compresing stabilizing mechanism comprising a centrifugally operated distributei' driven by an element of said stabilizing mechanism, a working circuit controlled by said distributer, an idling circuit controlled by said distributer, a main ignitioncircuit and means .f

for connecting said working circuit during operation under load to said ignition circuit and for replacing said working circuit by said idling circuit during periods of idling.

7. An ignition device for motor compressors having free-iiying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism comprising a coiled tube ada ted to respond to variations in pressure of t e compressed fluid supplied by the compressor, a switch lever operated by said tube, -means associated with said switch lever to cause the same to move abruptly, a main ignition circuit extending from saidV switch lever to the ground, a plurality lof contacts associated with said switch lever, a normal working circuit connected to `one of said contacts, an-'idling circuit connected to the other of said contacts, a distributer, brushes on said distributer, means for connecting said brushes to said working circuit and to said idling circuit respectively, means on said distributer for producing sparks at regular intervals when connected to said working circuit and for suppressing` certain of said sparks whenconnected to said -idling circuit and a ground connection for said last mentioned means.

8. In an ignition-A device for motor .compressors having free-flying direct -acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism, a distrbuter comprising* an operating shaft driven by.

an element of said stabilizing mechanism, an insulating contact drum on said shaft, contacts carried by said' drum, a brush associated with said contacts, a pivotally mounted contact pawl connected to one of said contacts on said drum, a stationary contact on said drum connected to the other of said first mentioned contacts associated with said -paw1, centrifugally operated'means f or moyf ing said pawl into engagement. with said stationary contact during oscillation of said drum, means for moving said Apawl away from said stationary contact during reversal of saidgdrum and means associated with said tain of the circuit opening movements of said pawlelectrically inoperative.

9. In an ignition device for motor compressors having free-flying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism, a distributer comprising an operating shaft driven by an elementf of said stabilizing mechanism, an

insulating contact drum on said shaft, contacts carried by said druma plurality of brushes associated with said contacts, a pivotally mounted contact pawl connected to one of said contacts on said drum, a stationary uContact on said drum connected to the other of/ said irst mentioned contacts associated with said pawl, centrifugally operated `means for moving said pawl into engagement with said stationary contact during oscillation of said drum, means for moving said pawl away from said stationary contact during reversal of said drum'and means associated with said pawl and said contacts for rendering certain of the 'circuit opening movements of said pawlelectrically inoperative at relatively different intervals with respect to said brushes.

10. In arf ignition device -for motor compressors having free-flying direct acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism, a distributer comprising an operating shaft driven by anelement of said stabilizing mechanism, an insulating contact drum on said shaft, a centrifugally closed interruptor on said drum, means for automatically opening said interrupter during reversal of said drum, means for automatically rendering certain of said opening operations electrically ineffective and means for assuring the opening of said interrupter in the event of an abnormal oscillation of said drum.

11. In an ignition device for motor compressors. having free-flyingdirect acting pistons interconnected by a non-kinematic uter comprising an operating shaft driven v by an element of said stabilizing mechanism,

12, In a distrbutei of the typ described ypawl and said contacts for rendering cer- Sti iioA

oscillating stabilizing mechanism, a distribi fpivotally' p a contact pawl; a centrifuga-l member operatively associated with said pawl and adapted to be moved in one direction by centrifugalvforce and in the other direction by a spring, a bell-crank having one arm attached to said spring, an insulated casing -for said distributer and a screw cover for said casing adapted to bear against the other arm of said bell-crank whereby the position of said cover on said casing determines the amount of tension in said spring.

13. In a distributer of the type describeda casing of insulating material, a cover screwed on said casing and means operated by the rotation of said cover for advancing and retarding the spark produced by said distributer. i4. In a device of the class described a distributer comprising a drum of insulating material, means on said drum for opening an ignition'circuit at regular intervals, a pair ot' contacts extending around theperiphery of said drum, two adjacent edges of said contacts being arranged parallelto each other and to the axis of the drum, the other two adjacent edges being arranged in over-lapping relation, a pair of brushes associated with said contacts disposed on opposite sides of said drum and means for placing said iirst mentioned means into electrical communicationwith said contacts anda ground connection for said first mentioned means Whereby the ignition circuit may be opened at regular intervals through one of said brushes and at different regular. intervals through the other of saidbrushes.

15. Inpa device of the class describeda distributer comprising a drum of insulating material, means on said drum for opening an ignition circuit at regular intervals, a pair of contacts extending around the periphery of said drum, two adjacent edges of said contacts being arranged parallel to each other and to the axis of the drum, the other two adjacent edges beingarranged in overlapping relation, a pair of brushes associated with said contacts disposed on opposite sides of said drum means for placing said first mentioned means into electrical communication with said contacts, a ground connection for said first mentioned means whereby the igni- -tion circuit may be opened at regular intervals through one of saidbrushes and at different regular intervals through the other of said brushes and means operated by the pressure of the` fluid compressed by the compressor for rendering one of said brushes operative when the compressor is operating under load and the other of said brushes operativewhen said compressorstarts to idle respectively.

16. An ignition device for motor compressorshaving' free-iiyingdirect acting pistons interconnected by a non-kinematic oscillating stabilizing mechanism comprising a centrifuname to this specification at' Barcelona,

Spain, this 24th day of March, 1927.

/ RAUL PATERAS PESCARA. 

